The present invention relates to a roll feed which may be used for feeding works to presses or the like.
The roll feed is a machine which holds a work between a pair of vertically aligned rolls, and feeds the work into dies of a press, for example, by intermittently rotating the rollers. Conventional roll intermittent rotation mechanisms, include a mechanical intermittent rotation mechanism, utilizing crank movement or other movement of the press, and an electrical intermittent rotation mechanism using a servomotor.
The mechanical intermittent rotation mechanism includes a one-way clutch type mechanism, a cam indexing type mechanism, etc. The one-way clutch type mechanism intermittently rotates rollers by a crank shaft through a drive rod and an oscillating lever whereas the cam indexing type mechanism intermittently drives the rollers by both a rotation cam, provided to the crank shaft, and an associated cam follower mounted on the roll side.
In the electrical intermittent rotation mechanism, there is a roll drive mechanism which intermittently rotates rollers by a servomotor. The rotation angle of the rollers is detected by an encoder or a pulse generator. By counting the number of pulses, the length of works fed is measured, and the results are fed back to the servomotor.
Recent presses require processing at a higher speed and a high accuracy. This requires high speed and high reliability for roll feeding. Other than high seed stability and high reliability, flexibility is required to meet and satisfy various other requirements, for example, in the case where works are to be fed at a high speed so as to synchronize to markings on works, and in the case where the roll feed is used for feeding works in secondary working in a high speed line.
In spite of these requirements, the conventional mechanical roll drive mechanism is difficult to control. More specifically, it is difficult to change the length of feed, feed speed and feed time although it is excellent in both high speed stability and reliability. On the other hand, the electrical roll drive mechanism is excellent in controllability but is inferior to the mechanical one in high speed feeding, stability, and reliability.